Control devices for bobbin thread replenishments in lockstitch sewing machines



March 10, 1970 GR i EI'AL 3,499,406

common DEVICES FOR BOBBIN THREAD REPLENISHMENTS IN LOGKSTITCH SEWING MACHINES Filed June 20, 1968 2 Sheets-Sheet 1 Robert G. Greullch,

BY Alfred H. Mack and John Blockwood WITNESS: W .66., dww Ja c-d AT ORNEY March 10, 1970 R. G. GREULICH ETAL 3,499,406

CONTROL DEVICES FOR BOBBIN THREAD REPLENISHMENTS IN LOCKSTITCH SEWING MACHINES 2 Sheets-Sheet 2 Filed June 20, 1968 INVENTORS' Robert G. Greulich, BY Alfred H. Mack and WITNESS: Weld.

John Blockwood I ATYORNEY United States Patent Ofi ice 3,499,406 CONTROL DEVICES FOR BOBBIN THREAD REPLENISHMENTS IN LOCKSTITCH SEW ING MACHINES Robert G. Greulich, Cranford, Alfred H. Mack, Linden, and John Blackwood, Bayonne, N.J., assignors to The Singer Company, New York, N.Y., a corporation of New Jersey Filed June 20, 1968, Ser. No. 738,428 Int. Cl. D05b 57/14, 59/00 US. Cl. 112-184 7 Claims ABSTRACT OF THE DISCLOSURE Background of the invention This invention relates to lockstitch sewing machines having mechanism for replenishing bobbin thread while the bobbin remains in place in the loop taker, and more particularly, to a novel and improved operator influenced arrangement for selectively shifting a thread winding element in the loop taker into a position for replenishing thread on the bobbin or into a position for sewing.

Prior known control mechanism whereby the operator might selectively accomplish shift of a thread winding element in the loop taker into effective or ineffective position for bobbin thread replenishment, as disclosed in the United States Patents Nos. 3,163,137 of Dec. 29, 1964, 3,374,755 of Mar. 26, 1968, and 3,374,756 of Mar. 26, 1968 in addition to providing operator influenced control elements such as push buttons, levers, or the like, include latch devices for maintaining the system in the effective bobbin thread replenishing position and latch release machanisms for restoring the parts to sewing con dition.

Brief summary of the invention It is an object of this invention to provide an operator influenced control arrangement of the above character which does not require a latch device for maintaining the system in the effective bobbin thread replenishing position and which, therefore, involves fewer, less complicated, and less critically dimensioned parts than those devices heretofore known.

It is also an object of this invention to provide an operator influenced control arrangement of the above character which can be located within the loop taker accommodating cavity in a sewing machine frame for exposure when a loop taker slide cover plate is retracted, as well as means for automatically shifting the control arrangement to an ineffective position when the loop taker slide cover plate is closed.

The aforementioned objects and advantages are provided in this invention by a control arrangement comprising a face cam angularly shiftable in the machine frame adjacent to the loop taker. A cam follower associated with the bobbin winding member engages directly and is influenced by the face cam. A rock shaft is secured to the face cam and to a rock arm which protrudes into the loop taker accommodating cavity for manual shift by the machine operator and for influence of position by closure of the loop taker slide plate cover.

3,499,46 Patented Mar. 10, 1970 Description of the drawings With the above and additional objects and advantages in view, as hereinafter appear, this invention comprises the devices, combinations, and arrangements of parts hereinafter described and illustrated in the accompanying drawings of a preferred embodiment in which:

FIG. 1 is a vertical cross sectional view of a sewing machine having the control arrangement of this invention applied thereto,

FIG. 2 is an enlarged top plan view of a portion of the bed of the sewing machine of FIG. 1 including loop taker accommodating cavity and in which a portion of the throat plate is broken away and the loop taker slide cover is open,

FIG. 3 is a cross sectional view taken substantially along line 33 of FIG. 2, and

FIG. 4 is a disassembled perspective view of the operator influenced control mechanism of this invention together with the bobbin winding element and the bobbin.

Description of the invention Referring to FIG. 1 of the drawings, this invention is illustrated embodied in a sewing machine including a frame formed with a work supporting bed 11 from which rises a standard 12 supporting a bracket arm 13 overhanging the bed. The stitch forming instrumentalities carried in the frame include an endwise reciprocatory threaded carrying needle 14 supported in the bracket arm 13 and a circularly moving loop taker 15 which is disposed within an upwardly open cavity 16 in the bed 11 and is journaled on a vertical axis in the bed by means of a bushing 17 in which a hollow loop taker shaft 18 is rotatable. Actuating mechanism is carried in the frame for operating the stich forming instrumentalities and includes a main drive shaft 19 in the bracket arm connected by means of a crank 20 to a needle bar 21 to which the needle 14 is clamped. The loop taker 15 1s actuated in timed relation with the needle reciprocation from the main drive shaft 19 by means of meshing gear sets 22, 23, and 24 and shafts 25 and 26.

Referring to FIGS. 2 and 3, the loop taker 15 is of the type which is adapted for replenishment of under or bobbin thread while the bobbin remains in place in the loop taker and while the needle and loop taker partake of their usual lockstitch forming. motions. This invention relates to the control mechanism by which the parts may be positioned selectively either to replenish the bobbin thread supply or to sew, and the loop taker construction by which bobbin thread replenishment may be accomplished does not form a direct part of this invention. The loop taker construction permitting bobbin thread replenishment is disclosed in detail in the United States Patent No. 3,115,855 filed Dec. 31, 1963, S. I. Ketterer to which reference may be had. For an understanding of this invention it will be sufficient to understand that a bobbin case in which is journaled relatively to a bearing rib 31 on the loop taker 15 and constrained from rotation with loop taker by a stop finger 32 and a rotation restraining spring 33 is formed with an annular seat 34 in which rests the upper flange 35 of a thread carrying bobbin 36. The bobbin is formed with a lower flange 37 of smaller diameter than the upper flange so as to depend freely through the bobbin case seat 34. A spring loaded lever 38 on the bobbin case 30 is formed with a protrusion 39 accommodated in a depression 40 in the upper flange 35 of the bobbin to constrain the bobbin in the annular seat 34 of the bobbin case. The lower flange 37 of the bobbin is formed with a recess 41 into which a tapered lug 42 protrudes.

For influencing selectively either replenishment of thread from the thread carrying needle onto the bobbin 3 36 or sewing, a bobbin winding member is disposed within the loop taker beneath the bobbin. The bobbin winding member is fast on a spindle 46 which is axially slideable in the hollow loop taker shaft 18. A washer 47 slotted as at 48 to key onto the slabbed lower extremity 49 of the spindle is formed with an upstanding finger 50 which is accommodated in a recess 51 in the bevel gear of the gear set 22 which is fast on the loop taker shaft 18 by means of the set screw 52 so that the bobbin winding member 45 will rotate in unison with the loop taker but is free to be shifted axially thereof into and out of engagement with the lower flange 37 of the bobbin. The bobbin winding member includes an annular upstanding rib 53 which envelops the lower flange of the bobbin when the bobbin winding member is raised, and the bobbin winding member also includes a drive lug 54 which is engageable with the tapered lug 42 in the recess beneath the bobbin to drive the bobbin when the bobbin winding member is raised. When the bobbin winding member is lowered, the

drive lug 54 will be shifted out of engagement with the tapered lug 42 On the bobbin and the top of the annular rib 53 on the bobbin winding member will be disposed beneath the level of the lower flange 37 of the bobbin so as not to interfere with the normal thread manipulation of the loop taker during stitch formation.

For selectively positioning the bobbin winding member 45 into and out of bobbin winding relation with the bobbin, a cam element is provided which is secured as by a set screw 61 to a rock shaft 62 journaled in the bed 11 adjacent and parallel to the loop taker shaft 18. Preferably the rock shaft 62 protrudes upwardly into the loop taker accommodating cavity 16 in the bed and fast on the rock shaft within the cavity 16 is a rock arm 63 which is thus accessible for influence by machine operator shift the cam element 60.

As illustrated in FIG. 3, the cam element 60 may comprise a metallic hub 64 in which the set screw 61 is threaded and onto which is molded a plastic cam body 65. The cam body is formed with an upstanding cam rib 66 of which the upper surface includes two spaced planar portions 67 and 68 disposed in parallel planes each plane perpendicular to the axes of the rock shaft 62 of the loop taker 15. Joining the spaced planar portions 67 and 68 is an inclined ramp portion 69.

Referring to FIGS. 3 and 4, a cam follower pin 70 is arranged to track the cam surfaces 67, 68, and 69 of the cam body, and the cam follower pin is slideable lengthwise in a blind bore 71 formed in the sewing machine bed 11 with a light coil spring 72 being constrained between the pin and the blind extremity of the bore to urge the cam follower pin into tracking relation with the cam. The bore 71 is preferably made parallel to the loop taker shaft 18 and a bracket member 73 which is secured to the cam follower pin as by a force fit thereon is formed with a downward offset 74 and a lateral limb 75 into which is formed a clearance aperture 76 closely embracing a shouldered nut 77 threaded onto the lower extremity of the spindle 46 on the bobbin winding member. The nut 77, therefore, maintains the bracket member 73 and the washer 47 in place axially on the lower extremity of the spindle 46 but because of the clearance aperture 76 on the bracket member 73, the spindle 46 is free to turn while the bracket member does not. As best illustrated in FIGS. 2 and 4, the cam body 65 includes a radially extending stop lug 78 at one side of the cam surfaces 67, 68, and 69 and an axial stop lug 79 at the other side of these cam surfaces. The stop lug 78 abuts the downward offset 74 of the bracket member 73 to limit turning movement of the cam element 69 in one direction, while the stop lug 79 abuts the side of the cam follow pin 70 to limit movement of the cam element on the opposite direction.

The loop taker accommodating cavity 16 in the sewing machine bed is covered in part by a throat plate 80 through slots 81 in which protrudes the teeth of conventional feed dog 32, The remainder of the loop taker accommodating cavity beneath which the major portion of the loop taker and the rock arm 63 of the control device of this invention are situated, may be closed by a slide cover plate 83. The slide cover plate is formed at each side with a depending rib 84 and 85, which ribs provide guide surfaces engaging the edges of the cavity 16 for constraining the slide cover plate thereon. A leaf spring 86 may be used as is conventional to constrain the slide cover plate slidingly on the cavity 16. As illustrated in FIG. 2, the rock arm 63 can be turned in a counterclockwise direction to shift the cam element 60 only when the slide cover plate 83 has been retracted. When the slide cover plate 83 is shifted to close the cavity 16, the rib on the slide cover plate will automatically engage and force the rock arm into the full line position as illustrated in FIG. 2 which will shift the lower planar cam surface 67 into engagement with the cam follower pin 70 to lower the bobbin winding member into the sewing position. It will be apparent, therefore, that although the rock arm 63 may be shifted into either sewing or bobbin threading position while the slide cover plate is retracted, the rock arm in any event will be shifted into sewing position upon closure of the slide cover plate.

The rock arm 63 may be of any shape and configuration which will meet the space requirements alongside the loop taker in the loop taker accommodating cavity in the bed, it is pointed out that the rock arm 63 must be turned in its operation and not depressed. It has been found that a simple pushing motion on the part of the operator is an extremely simple and effective maneuver. For this reason the upper surface 90 of the rock arm 63 may advantageously be formed not only to radiate from the rock shaft 62 substantially perpendicular to the axis of the rock shaft, i.e., in the direction RR as indicated in FIG. 4, but also to extend substantially in an inclined plane with which the axis X-X of the rock shaft 62 intersects at an acute angle. The line FF illustrated in FIG. 4 is drawn substantially within the inclined plane of the upper surface 90, and the angle marked b thereon indicates the acute angle which this plane forms with the axis X-X of the rock shaft 62. While the degree of angularity b of the surface 90 is not critical, an angle b approaching 45 has been found to be highly effective in that a downward force applied against such an angular surface 90 perpendicular to the rock shaft axis will give rise to a component of force in the rock arm generating torque in the rock shaft. While counterclockwise motion of the rock arm as viewed in FIGS. 2 and 4 is all that is required by direct contact of the rock arm by the operators finger because closure of the slide cover plate will automatically shift the rock arm in a clockwise direction, such inclination of the upper surface of the rock arm permits this mechanism to respond in a manner very similar to a push button operated device.

Having set forth the nature of this invention, What is claimed herein is:

1. A control mechanism for bobbin thread replenishment in a lockstitch sewing machine having a frame, a circularly movable loop taker journaled in said frame, a thread carrying bobbin supported within said loop taker, a bobbin winding element carried with said loop taker for circular movement therewith, and means supporting said bobbin winding element for axial shift relatively to said loop taker into and out of driving relationship with said thread carrying bobbin, said control mechanism comprising a cam follower means arranged exteriorly of said looptaker and connected with said bobbin winding element for axial shift therewith relatively to said loop taker, cam means shiftably supported on said frame adjacent to said loop taker and including a cam surface varying in a direction axially of said loop taker and disposed for engagement by said cam follower means, and operator influenced means carried on said frame for shifting said cam surface relatively to said cam follower means.

2. A control mechanism for bobbin thread replenishment as set forth in claim 1 in which said cam means is fast on a rock shaft journaled in said frame on an axis substantially parallel to the axis of said circularly moving loop taker and in which said operator influenced means includes a rock arm secured to said rock shaft.

3. A control mechanism for bobbin thread replenishment as set forth in claim 2 in which said rock arm radiates from said rock shaft substantially perpendicular to the axis of said rock shaft and the upper exposed face of said rock arm intersects said axis at an acute angle so that a force applied apainst said exposed face in a direction parallel to the rock shaft axis will give rise to a component of force in said rock arm generating a torque in said rock shaft.

4. A control mechanism for bobbin thread replenishment as set forth in claim 1 in which said cam surface includes two spaced planar portions disposed in parallel planes each plane extending perpendicular to the axis of said loop taker, and an inclined ramp portion joining said spaced planar portions.

5. A control mechanism for bobbin thread replenishment as set forth in claim 4, in which said cam means includes stop lugs projecting beyond said cam surface and arranged for engagement of each stop lug with an opposite side of said cam follower means to limit shifting of said cam surface relatively to said cam follower means.

'6. A control mechanism for bobbin thread replenishment as set forth in claim 1 in which said cam followed means comprises a plunger, means slideably constraining said plunger in said frame to move endwise along a path parallel to said loop taker axis, a bracket secured to said plunger, bearing means in said bracket rotatively accommodating said bobbin winding element, and means constraining said bobbin winding element to shift axially with said bracket.

7. A control mechanism for bobbin thread replenishment as set forth in claim 3 in which said frame is formed with an upwardly open loop taker accommodating cavity closed at the top by a slide cover plate in which said loop taker is journaled on a vertical axis within said loop taker accommodating cavity, in which the rock arm of said operator influenced means extends within said loop taker accommodating cavity alongside said loop taker for exposure when said slide cover plate is opened, and means on said slide cover plate and on said rock arm cooperating when said slide cover plate is closed to position said rock arm in a predetermined angular position in which said bobbin winding element is shifted out of driving relationship with said thread carrying bobbin.

References Cited UNITED STATES PATENTS 3,374,756 3/1968 Blackwood et al 1l2l84 3,407,760 10/1968 Ketterer 112-184 H. HAMPTON HUNTER, Primary Examiner U.S. Cl. X.R. 112l86 

